The present disclosure relates to a portable system which is especially suitable for use in extracting iodine from an aqueous solution containing soluble iodine ions, such as brine.
Elemental iodine is a valuable chemical having many industrial and medicinal applications. There is an increasing demand for iodine and its major derivatives, iodide salts. The consumption of iodine and iodide salts is distributed among several industrial applications, such as catalysts, animal feed additives, stabilizers for nylon resins, inks and colorants, pharmaceuticals, disinfectants, film, and other uses. Much attention is therefore focused on the recovery of iodine from various sources, either as a primary product or as a by-product of other industrial processes.
Iodine recovery is generally carried out by physical or chemical manipulation of an aqueous solution containing soluble ions of iodine. Exemplary solutions include leaching solutions used in nitrate extraction and brine solutions. The term “brine” in this context includes industrial and naturally occurring salt solutions containing iodine in various salt forms. Exemplary brines are seawater and natural brines such as those associated with petroleum deposits and with solution mining of salt domes.
The United States accounts for only 5% of global production, and domestic producers of iodine supply only about 28% of domestic demand, with the remainder being imported.
Iodine has been isolated from gas well brine for over 80 years in various fields in Japan and Oklahoma. The brine is pumped from a number of gas wells over many miles to a centralized processing facility. In that facility, the iodide rich brine is acidified and oxidized to obtain elemental iodine (I2). In Japan, the iodine is then adsorbed, for example using anion exchange resins or carbon, to concentrate the iodine. The adsorption media is then “stripped” of iodine by a number of techniques. In Oklahoma, the iodine is recovered from a “blow out tower” where the iodine is vaporized by heat and an air stream blowing through the oxidized brine condenses the vaporized iodine as a solid that is recovered. In either case, the leftover brine, with iodine removed, is then sent back to the field and typically injected back into the ground.
High capital expenditures (in the tens of millions of dollars) are associated with a centralized processing facility. There is also substantial investment in each gas well, which is typically drilled to a depth of about 2,000 meters, and in the pipeline needed to carry the brine over a distance of many miles from the gas well to the centralized processing facility. High risk is also present because the brine production capacity of a gas well is unknown at the time the capital expenditure needs to be made. A gas well may produce for only a year, which reduces the return on investment. However, a better model has not yet been implemented in the past 80 years.
It would be desirable to provide a system that can reduce capital expenditures and provide safe, economical iodine extraction from such natural brines.